With its sumptuous palaces and a library that stored all human knowledge, Alexandria was the envy of the ancient world.

And the great lighthouse that stood sentinel on the island of Pharos in the city's harbour was its radiant beacon.

Alexandria was founded by Alexander the Great, who wanted a symbol of his power to light up all Egypt and beyond. But it was his successor, the general Ptolemy - the Greek pharaoh of Egypt - who fulfilled his vision and began the lighthouse in 260 BC.

It was completed by Ptolemy's son around 20 years later, the same year another Wonder of the World, the Colossus of Rhodes, was completed.

The lighthouse was built on Pharos, a limestone outcrop on the northwest coast of the Nile Delta, first mentioned by Homer in The Odyssey.